1. Field of the Invention
The present invention relates to a manufacturing method of an SOI substrate.
2. Description of the Related Art
Instead of a silicon wafer which is manufactured by thinly slicing an ingot of a single crystal silicon, a substrate in which a thin semiconductor layer is provided on an insulating surface (hereinafter also referred to as an SOI substrate; the term “SOI substrate” is generally used as an abbreviation of “Silicon on Insulator”; however, in this specification, it is not necessary to limit a semiconductor film formed on an insulating surface to a silicon film and therefore the term “SOI substrate” is used as an abbreviation of “Semiconductor on Insulator”) is manufactured and is used for manufacturing semiconductor integrated circuit elements or the like.
As a method for manufacturing an SOI substrate, a method in which hydrogen ions are added to a semiconductor substrate is known (for example, see Patent Document 1). In the method, first, an insulating layer (e.g., a thermal oxide film) is formed on a surface of a semiconductor substrate (e.g., a single crystal silicon substrate), and hydrogen ions are added to the semiconductor substrate through the surface where the insulating layer is formed, so that a dangling bond is terminated by added hydrogen ions and a microbubble region (in this specification, also referred to as an embrittlement region) is formed at a predetermined depth which is the neighborhood of the surface. Next, a different substrate (e.g., a glass substrate, a silicon wafer) is bonded to the surface side of the semiconductor substrate where the microbubble region is formed, and heat treatment is performed. Consequently, hydrogen ions in the semiconductor substrate are gathered in the micro-bubble region and a cleavage phenomenon occurs in the micro-bubble region, so that a semiconductor thin film layer separated from the semiconductor substrate and the insulating layer formed in contact with the semiconductor thin film layer can be transferred to the different substrate.